Effect of acute physiologic derangements on outcome after subarachnoid hemorrhage*

Abstract

OBJECTIVE: To determine the effect that acute physiologic derangements have on outcome after subarachnoid hemorrhage (SAH) and to design a composite score summarizing these abnormalities. DESIGN: Prospective observational study. SETTING: Neuroscience intensive care unit in a tertiary care academic center. PATIENTS: Consecutive cohort of 413 patients with SAH admitted within 3 days of SAH onset with 3-month modified Rankin Scale scores. INTERVENTIONS: None. RESULTS: Among 20 physiologic variables assessed within 24 hrs of admission, four were independently associated with death or severe disability (modified Rankin Scale score, 4-6) at 3 months in a multivariate analysis: arterio-alveolar gradient of >125 mm Hg (odds ratio [OR], 4.5; 95% confidence interval [CI], 2.7-7.6), serum bicarbonate of <20 mmol/L (OR, 2.9; 95% CI, 1.6-5.6), serum glucose of >180 mg/dL (OR, 2.8; 95% CI, 1.6-4.8), and mean arterial pressure of <70 or >130 mm Hg (OR, 1.7; 95% CI, 1.0-2.9). Based on their proportional contribution to outcome, we constructed the SAH Physiologic Derangement Score (SAH-PDS; range, 0-8) by assigning the following weights for abnormal findings: arterio-alveolar gradient, 3 points; bicarbonate, 2 points; glucose, 2 points; and mean arterial pressure, 1 point. After controlling for known predictors of death or severe disability (age, admission neurologic status, loss of consciousness, aneurysm size, intraventricular hemorrhage, and rebleeding), the SAH Physiologic Derangement Score was independently associated with poor outcome (OR, 1.3 for each point increase; 95% CI, 1.1-1.6). By contrast, the systemic inflammatory response syndrome score and the Acute Physiology and Chronic Health Evaluation II physiologic subscore did not add predictive value to the model. CONCLUSION: Acute interventions specifically targeting hypoxemia, metabolic acidosis, hyperglycemia, and cardiovascular instability may improve the outcome of SAH patients. The SAH Physiologic Derangement Score may prove useful for rapidly quantifying the severity of important physiologic derangements in acute SAH.